A Weighted Viewport Quality Metric for Omnidirectional Images

Huyen T. T. TRAN  Trang H. HOANG  Phu N. MINH  Nam PHAM NGOC  Truong CONG THANG  

IEICE TRANSACTIONS on Information and Systems   Vol.E103-D   No.1   pp.67-70
Publication Date: 2020/01/01
Publicized: 2019/10/10
Online ISSN: 1745-1361
DOI: 10.1587/transinf.2019MUL0002
Type of Manuscript: Special Section LETTER (Special Section on Enriched Multimedia — Application of Multimedia Technology and Its Security —)
omnidirectional images,  objective quality metrics,  

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Thanks to the ability to bring immersive experiences to users, Virtual Reality (VR) technologies have been gaining popularity in recent years. A key component in VR systems is omnidirectional content, which can provide 360-degree views of scenes. However, at a given time, only a portion of the full omnidirectional content, called viewport, is displayed corresponding to the user's current viewing direction. In this work, we first develop Weighted-Viewport PSNR (W-VPSNR), an objective quality metric for quality assessment of omnidirectional content. The proposed metric takes into account the foveation feature of the human visual system. Then, we build a subjective database consisting of 72 stimuli with spatial varying viewport quality. By using this database, an evaluation of the proposed metric and four conventional metrics is conducted. Experiment results show that the W-VPSNR metric well correlates with the mean opinion scores (MOS) and outperforms the conventional metrics. Also, it is found that the conventional metrics do not perform well for omnidirectional content.